Reciprocating piston type actuators



Sept. 28, 1965 H. ALLEN ETAL RECIPROCATING PISTON TYPE ACTUATORS 2 Sheets-Sheet 1 Filed Nov. 19, 1963 a WR "Mm w AKW f I i Z :5

ATTORNEYS Se t 28, 1965 H. ALLEN ETAL 3,208,357

RECIPROCATING PISTON TYPE ACTUATQRS Filed Nov. 19, 1963 2 Sheets-Sheet 2 1 Robe/'7 K. LeEoaax i INVENTOR.

United States Patent 3,208,357 RECIPROCATING PISTON TYPE ACTUATORS Herbert Allen and Robert K. Le Rouax, Houston, Tex., assiguors to Cameron Iron Works, Inc., Houston, Tex., a corporation of Texas Filed Nov. 19, '1963, Ser. No. 324,633 7 Claims. ((31. 9'227) This invention relates generally to reciprocating piston type fluid actuators, and, more particularly, to an improved device for locking such an actuator and thus the part to be actuated in a desired position.

One environment in which such devices have been found particularly useful is in the locking of the rams of oil and gas well blowout preventers in closed positions. In these blowout preventers, fluid actuators move the rams inwardly from opposite sides of the bore through the preventer body so as to cause the inner ends of the rams to engage against one another in either sealing across the open bore or about a pipe in the bore. Generally, each ram carries a strip of rubber which includes a portion protruding from its end face for initial engagement with a similar portion of the end face of the other ram. Upon continued urging of the rams toward one another, the protruding rubber portions of the seal strips are deformed so as to not only form a tight seal between the ram faces, as well as between the ram faces and a pipe in the bore, but also deform other portions of the seal strips into sealing engagement between the rams and the preventer body to thereby close off the bore.

In one common type of locking device for a reciprocating piston type actuator, a lock member is laterally movable into engagement with a notch along the length of the piston rod when the piston is in the position in which it is to be locked. However, this type of device is unsuitable for locking blowout preventer rams, wherein tolerances between the rams, fluid actuators, and intermediate connecting parts may stac and further wherein the seal strips across the faces of the rams will wear. That is, since the relative locations of the locking parts of such a device are fixed in the direction of reciprocation of the piston, it might well be found that the rams could not be locked in tightly sealing positions.

Thus, it has been proposed to lock blowout preventer rams in closed positions by means of screws carried by the preventer for extension into and retraction from locking position in the direction of movement of the actuator piston. In this way, the locking device can compensate for stacked tolerances as well as Wear on the sealing member. However, the operation of lock screws is particularly unsuited for use in underwater or other remote loca tions where it is impractical to transmit a rotary movement to the lock screws.

An object of this invention is to provide a fluid actuator having a device which is especially well suited for locking remotely located blowout preventer rams or the like.

Another object is to provide a locking device for a fluid actuator which will compensate for the stacking of tolerances between it and the actuated part, as well as for wear upon the actuated part, and which at the same time is easily and quickly operable from a remote location.

A further object is to provide a locking device of the character described in the foregoing object, which is separately connectible to and removable from a fluid actuator, whereby it may be replaced or repaired independently of the actuator or, for that matter, installed upon existing equipment.

These and other objects are accomplished, in accordance with the illustrated embodiment of the invention, by a fluid actuator of the type described having a pair of rods extending from the piston and through the cylinder thereof. One of these rods is adapted for connection to the part to be actuated, while the other rod is adapted to be engaged by a lock member to hold such actuated part in a desired position. More particularly, when the actuated part is the ram of a blowout preventer, the lock member will hold the ram in tight sealing engagement with an opposite ram to close the bore of the preventer body. When the lock member is disengaged from such part, it is then free to be moved by the actuator to an alternate position. In the case of a blowout preventer ram, this may be a position spaced from its opposite ram so as to open the bore of the preventer body. The rod may be a tail rod for the piston of the actuator and thus extend from the end of the cylinder opposite to the end through which the first-mentioned rod extends.

The lock member is mounted for movement between a first position to one side of the other rod so as to permit the piston of the actuator to move into the alternate position, and a second position laterally across the outer end of the rod so as to hold said piston in the desired position. More particularly, the lock member has a wedge surface which, in the preferred embodiment of the invention, slidably engages over a complementary wedge surface on the outer end of the other rod as the lock member moves into second position. In this way, the locking device takes up for tolerances in the connections between the lock member and part to be actuated as well as for wear on the latter.

The lock member is moved between its first and second positions by hydraulic means which enables operation of the device at a remote location, as, for example, in the case of a blowout preventer on an underwater well. More particularly, the wedge surfaces on the lock member and end of the rod are tapered an angle which is less than the friction angle between them so that, in the event the pressure on the hydraulic system is removed, either intentionally or accidentally, the lock member will nevertheless remain fixed in locking position across the outer end of the other rod until positively returned to its first position upon return of hydraulic pressure.

If the locking device is to be used on an existing actuator, or if, for example, it is desired that the device be readily removable and replaceable from the actuator, it may comprise a body separate from the actuator and having a bore which, upon connection of the body to the actuator, receives the tail rod of the actuator piston. A guideway within the body extends across the bore intermediate the ends of the bore, and the lock member is mounted on a carrier which is reciprocated between alternate positions Within the guideway by means of an bydraulic operator. This carrier has an opening through it to one side of the lock member for alignment with the bore in the body in one alternate position of the carrier so as to permit extension of the rod through it. However, as the part to be actuated is moved to the desired position and the carrier is moved from its one to its other alternate position, the outer end of the tail rod is withdrawn from the opening to permit the wedge surface on the lock member to slide over the outer end of the rod.

In the drawings, wherein like reference characters are used throughout to designate like parts:

FIG. 1 is a horizontal cross-sectional view of one side of a blowout preventer having a locking device for the fluid-actuated ram thereof constructed in acordance with the present invention, and with the lock member of such device moved to a position to permit the fluid actuator to retract the ram to open position;

FIG. 2 is a view similar to FIG. 1, but with the actuator moved to a position for closing the ram and the locking member of the locking device moved into locking position over the end of the tail rod on the piston of the actuator;

FIG. 3 is an enlarged horizontal sectional view of the locking device of FIGS. 1 and 2, and with the tail rod and lock member of the locking device in the positions shown in FIG. 1; and

FIG. 4 is a cross-sectional view of part of the tail rod and carrier of the locking device, as seen along broken line 4-4 of FIG. 3.

With reference now to the details of the above-described drawings, the blowout preventer shown in part in FIGS. 1 and 2 is identical to that shown and described in a copending application entitled Blowout Preventer, which was executed by Herbert Allen on October 23, 1963, Serial No. 319,284, filed October 28, 1963, and assigned to the assignee of the present application. Obviously, of course, this particular blowout preventer construction is shown and described merely for purposes of illustration, and it may be one of more conventional construction. Also, although the locking device is particularly well suited for use in locking blowout preventer rams in closed positions, it will be understood that it has other uses, particularly in environments Where similar problems occur insofar as locking the actuated part is concerned.

At any rate, and as more fully described in such other application, this blowout preventer, which may be disposed at an underwater location, includes a body 11 having a bore 12 therethrough and guideways 13 therein connecting with opposite sides of the bore. As well known in the art, the upper and lower ends (not shown) of the preventer body are adapted to be connected as part of the wellhead with the bore 12 therethrough forming a continuation of the well bore to receive pipe as it is lowered into and raised from the well bore.

A ram 14 is slidable within each of the guideways between the retracted position of FIG. 1 so as to open the bore and the extended position of FIG. 2 so as to close the bore. These rams may be of the blind variety, as shown in FIGS. 1 and 2, for closing off an open bore. Alternatively, the inner ends of the rams may be shaped for sealing about a pipe in the bore as well as with one another on each side of the pipe. In either case, each ram 14 includes a metal body 17 having a rubber seal strip thereon which includes a portion 15 (see FIG. 1) extending across its inner face as well as a portion 16 extending across the top side of the ram body as well as along each side thereof between the top side and inner face portion 15. As can be seen from FIG. 1, the portion 15 of the seal strip protrudes outwardly from the front end of the body 17 of the ram for engagement with a similar portion on the opposite ram as the rams are first brought together. Then, upon continued urging of the rams toward one another, the protruding seal strip portions 15 are distorted inwardly so as to form a tight seal thereacross and cause the seal strip portions 16 to expand and seal tightly between the ram and the guideway in which the ram is movable. As noted above, the fully closed positions of the rams longitudinally of the guideways may change upon wear of the seal strip portion 15.

The outer end of each guideway 13 is closed by a b n t 18 c nne ted to t e b y 11 y ui e e such as that shown and described in the earlier application, and the actuator for moving the ram 14 between the above-described open and closed positions comprises a cylinder 19 in the bonnet, a piston 20 reciprocable within the cylinder, and a rod 21 on the piston extending through the inner side of the bonnet 18 for connection to the ram. More particularly, the piston is caused to reciprocate within a liner 22 in the cylinder 19 by means of fluid pressure alternately applied to and exhausted from its opposite sides through ports 23 and 23a into the cylinder connected with the inner and outer sides, respectively, of the piston.

In the particular blowout preventer shown in FIGS. 1 and 2, each bonnet 18 is supported from the body 11 for movement toward and away from its position connected across the end of the guideway 13 by means of a pair of rods 24 connected to the body at their inner ends and carrying pistons 25 at their outer ends. More particularly, the pistons are sealably slidable within liners 26 carried within cylinders 27 extending parallel to the cylinder 19 on each side thereof to provide fluid actuators for moving the bonnet relative to the body 11. For this purpose, it is merely important to note that pressure fluid is alternately fed to and exhausted from opposite sides of the pistons 25 of the bonnet actuators by means of passages 28 and 29 and ports 30 and 31 in the body 11, which connect with passages 24a extending through the rods 24. The passage through the left rod connects with port 23 and the passage through the right rod connects with port 23a, so that pressure fluid introduced into the preventer through external port 30 will be directed to the outer side of the actuator piston 20 for moving the ram 14 to its closed position, while pressure fluid introduced through port 31 will be applied to the inner side of piston 20 for moving the ram to the open position of FIG. 1. Obviously, in a more simplified arrangement of the hydraulic system, the hydraulic fluid could be introduced more directly to the inner and outer sides of the actuator piston 20.

A tail rod 32 on the outer side of piston 20 extends through the outer side of the cylinder 19 formed in the bonnet 18. In the embodiment shown, the tail rod includes a main portion 32a connected to the piston and an adapter 33 removably connected to the end thereof by means of a pin 34 or the like. This adapter provides the outer end of the tail rod with a wedge surface 35 disposed for engagement by a lock member 36 of the locking device in a manner to be described. This two part construction of the tail rod permits locking of the blowout preventer rams by other lock members which do not require a wedge surface, such as the lock screw shown in the aforemtioned pending application. Thus, the locking device of this invention may be replaced by this other type of device when, for example, the preventer is to be used above the water level.

The lock member 36 is mounted for reciprocation within the guideway 37 of a body 38 between the position of FIG. 2, wherein it is disposed over the outer end of the rod 32 to lock the ram closed, and the unlocking position of FIG. 1 to one side of the rod 32 to permit the rod to be moved outwardly as the ram 14- is moved to its open position. More particularly, the tail rod is received within a bore 39 in the body 38 which is intersected intermediate its ends by the guideway 37 when the body is removably connected to the bonnet 13 of the preventer by means of screws 40.

As best shown in FIG. 3, the lock member 36 has a wedge surface 41 along its inner side which is complementary to the wedge surface 35 on the outer end of the tail rod over which it slides upon movement of the lock member into the locking position of FIG. 2. More particularly, the lock member 36 is mounted on a carrier 42 having pressure responsive surfaces 43 and 44 on its opposite ends which face the closed ends of the guideway 37 provided by heads 45 and 46.

As best shown in FIG. 3, a rod 47 extends from the head 45 into a recess 48 in the lock member portion of the carrier 42 and has a piston 49 on its end which is sealably slidable within the recess. A passageway 50 extends through the rod for connection at one end with an externally connecting port 51 in the head 45 and at the other end with the pressure chamber formed between pressure responsive surface 43 on the carrier and the oppositely facing pressure responsive surface 52 on piston 49. Thus, the introduction of hydraulic fluid into the port 51 will urge the carrier 42 and thus the lock member 36 to the right as shown in FIG. 3, or in a locking direction.

The pressure responsive surface 44 comprises the face of a piston 44a on the right-hand end of the carrier sealably slidable in guideway 37, and an externally connecting port 53 in the head 46 permits the introduction of hydraulic fluid into the chamber between the inner side of such head and the piston on the carrier 42 so as to urge the carrier to the left, or in an unlocking direction. Thus, the selective introduction and exhaustion of hydraulic fluid into and out of the external ports 51 and 53 will enable the carrier and thus the lock member to be reciprocated between its locking and unlocking position. More particularly, suitable lines may connect the ports 51 and 53 with a source of hydraulic fluid at a convenient location, such as above the water level, so that, as previously described, this hydraulic operator enables the selective locking and unlocking of the fluid actuator for the preventer rams, even though disposed at an otherwise inaccessible location.

There is an opening 54 in the carrier 42 between the lock member 36 thereon and the piston 44a on the righthand end of the carrier. More particularly, this opening is of a size and so located as to receive the tail rod of the ram actuator therethrough in the open position of the ram. However, upon movement of the actuator inwardly so as to close the ram, the tail rod also moves inwardly or downwardly as shown in FIG. 3, so as to dispose its wedge surface 35 in position to be slidably engaged by the wedge surface 41 on lock member 36.

The guideway and at least a portion of the carrier 42 closely fittable within it are non-circular in cross section, so as to maintain the wedge surface in a fixed planar relationship to the direction of reciprocation of the tail rod 32. The tail rod, which is circular in cross section, is maintained against rotation by means of a pin 55 thereon which moves longitudinally within a slot 56 extending from the opening 54 in the carrier and a continuation 57 of the slot formed in the body 38 of the locking device. Thus, the wedge surface 35 on the outer end of the tail rod is positioned for sliding engagement by the wedge surface 41.

The outer end of the bore 39 is closed by a plug 58 so as to prevent the accumulation therein of extraneous matter which might damage the pistons of the operator. This plug preferably carries a conventional check valve 59 to permit easy reciprocation of the tail rod within the body of the locking device.

In the preferred form of the invention, each of the wedge surfaces 41 on the locking device 36 and the wedge surface 35 of the tail rod are tapered at an angle which is less than the friction angle therebetween. That is, the angle formed between these surfaces and a line perpendicular to the axis of reciprocation of the tail rod is less than the friction angle between these sliding surfaces which, of course, depends on the material from which these parts are made. With such a construction, these surfaces will maintain the actuator closed even though the hydraulic pressure on the closing side of the carrier is lost, as would occur, for example, if the line leading to port 51 were to be broken.

Once the locking surface 41 has been forced against wedge surface 35, it will in time take a set. However, the pressure responsive surface on piston 44a is larger 6 than that on piston 49, so that the locking member may be moved back to unlocking from the same source that is employed in the movement of such member to locking position.

From the foregoing, it will be seen that this invention is one well adapted to attain all of the ends and objects hereinabove set forth, together with other advantages which are obvious and which are inherent to the apparatus.

It will be understood that certain features and subcombinations are of utility and may be employed without reference to other features and subcombinations. This is contemplated by and is within the scope of the claims.

As many possible embodiments may be made of the invention without departing from the scope thereof, it is to be understood that all matter herein set forth or shown in the accompanying drawings is to be interpreted as illustrative and not in a limiting sense.

The invention having been described, what is claimed 1s:

1. A fluid actuator, comprising a cylinder having a piston reciprocable therein between alternate positions, a rod on the piston extending through the cylinder for connection with a part to be actuated, another rod on the piston extending through the cylinder, a lock member mounted for movement between a first position to one side of the other rod, when said piston is in one alternate position, and a second position laterally across the outer end of the other rod, when said piston is in the other alternate position, and hydraulic means for moving the lock member between said first and second positions, said lock member having a wedge surface slid- .ably engageable over a wedge surface on said outer end of the other rod as said lock member is moved into said second position.

2. In a fluid actuator having a cylinder with a piston reciprocable therein between alternate positions and a rod on the piston extending through the cylinder for connection with the part to be actuated; another rod on the piston extending through the cylinder, a lock member movable in opposite directions transverse to the direction of reciprocation of the piston between a first position to one side of the other rod, to permit said piston to move to one of its alternate positions, and a second position across the outer end of said other rod to lock said piston in its other alternate position, and means for hydraulically moving said lock member between its first "and second positions, said locking member and said outer end of said other rod having complementary surfaces thereon which are tapered at an angle which is less than the friction angle therebetween for slidably engaging with one another as the lock member moves into said second position.

3. In a fluid actuator having a cylinder with a piston reciprocable therein between alternate positions, a rod on the piston extending through one end of the cylinder for connection with the part to be actuated, and a tail rod on the piston extending through the opposite end of the cylinder; a lock member reciprocable between a first position in which it is disposed to one side of the tail rod, when said rod is moved to one of its alternate positions, and :a second position in which it is disposed across the outer end of the tail rod, when said piston is in its other alternate position, said lock member having a wedge surface thereon slidably engageable over said outer end of the tail rod as said lock member moves into said second position, and hydraulic means for moving said lock member between said first and second positions.

4. A device for locking a reciprocating piston type fluid actuator in one position, wherein said. piston has a tail rod thereon extending through one end of the cylinder thereof, comprising a body having a bore therein, means for connecting the body to the actuator with its bore receiving the tail rod during reciprocation of the piston, a guideway in the body extending across the bore position by hydraulic fluid intermediate the ends of the bore, and a carrier having a lock member within the guideway, hydraulic means for reciprocating said carrier between alternate positions within said guideway, said carrier having an opening therethrough to one side of the lock member and alignable with the bore in the body in one alternate position thereof to permit extension of the end of the rod therethrough, and said lock member having a wedge surface thereon for slidably engaging over the outer end of the rod when said piston of the actuator is in said one position and said carrier is moved from said one to its other alternate position. A

5. A device of the character defined in claim 4, Wherein there is a Wedge surface on the outer end of said tail rod complementary to the wedge surface on said lock member, and both of said wedge surfaces are tapered at an angle which is less than the friction angle therebetween.

6. A device of the character defined in claim 5, wherein said hydraulic means comprises oppositely facing pressure responsive surfaces on the carrier, the surface responsive to pressure for moving said carrier to its one alternate position being larger than the surface responsive to pressure for moving said carrier to its other alternate position.

7. A device of the character defined in claim 4, including a Wedge surface on the outer end of the tail rod complementary to the wedge surface of the lock member, and means for maintaining said wedge surfaces in parallel relation.

No references cited.

RICHARD B. WILKINSON, Primary Examiner. 

1. A FLUID ACTUATOR, COMPRISING A CYLINDER HAVING A PISTON RECIPROCABLE THEREIN BETWEEN ALTERNATE POSITIONS, A ROD ON THE PISTON EXTENDING THROUGH THE CYLINDER FOR CONNECTION WITH A PART TO BE ACTUATED, ANOTHER ROD ON THE PISTON EXTENDING THROUGH THE CYLINDER, A LOCK MEMBER MOUNTED FOR MOVEMENT BETWEEN A FIRST POSITION TO ONE SIDE OF THE OTHER ROD, WHEN SAID PISTON IS IN ONE ALTERNATE POSITION, AND A SECOND POSITION LATERALLY ACROSS THE OUTER END OF THE OTHER ROD, WHEN SAID PISTON IS IN THE OTHER ALTERNATE POSITION, AND HYDRAULIC MEANS FOR 